__Motivation__
`HttpClientCodec` skips HTTP decoding on the connection after a successful HTTP CONNECT response is received.
This behavior follows the spec for a client but pragmatically, if one creates a client to use a proxy transparently, the codec becomes useless after HTTP CONNECT.
Ideally, one should be able to configure whether HTTP CONNECT should result in pass-through or not. This will enable client writers to continue using HTTP decoding even after HTTP CONNECT.
__Modification__
Added overloaded constructors to accept `parseHttpPostConnect`. If this parameter is `true` then the codec continues decoding even after a successful HTTP CONNECT.
Also fixed a bug in the codec that was incrementing request count post HTTP CONNECT but not decrementing it on response. Now, the request count is only incremented if the codec is not `done`.
__Result__
Easier usage by HTTP client writers who wants to connect to a proxy but still decode HTTP for their users for subsequent requests.
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